Total securities. As of June 30, 2024, our total debt securities were $601.0 million excluding the allowance for credit loss, representing an increase of $23.2 million, or 4.0%, compared to $577.8 million as of June 30, 2023. The increase was primarily driven by bond maturities being reinvested into U.S. government treasuries, as well as a decrease in gross unrealized losses within the available for sale securities portfolio. As of December 31, 2023, our total securities were $566.5 million, representing a decrease of $25.6 million, or 4.3%, compared to $592.2 million as of December 31, 2022. This decrease reflected our strategic decision to selectively reinvest proceeds from matured securities and maintain a higher cash reserve, aligning with our goal to enhance liquidity and support anticipated needs.
U.S. government treasuries. U.S. government treasuries represent debt securities backed by the U.S. Treasury or the full faith and credit of the U.S. government and are guaranteed as to the timely payment of interest and principal when held to maturity. As of June 30, 2024, our U.S. government treasuries increased by $50.7 million, or 26.2%, compared to June 30, 2023. As of December 31, 2023, our U.S. government treasuries decreased by $4.7 million, or 2.4%, compared to the prior year.
U.S. federal agencies securities. U.S. federal agencies securities represent obligations issued by U.S. federal government agencies or government-sponsored enterprises that guarantee repayment of principal at maturity. As of June 30, 2024, our U.S. federal agencies securities decreased by $6.3 million, or 25.5%, compared to June 30, 2023. As of December 31, 2023, our U.S. federal agencies securities decreased by $3.9 million, or 15.7%, compared to the prior year.
Mortgage backed securities. Our mortgage backed securities portfolio consists of pass through and agency-issued collateralized mortgage obligations. As of June 30, 2024, our mortgage backed securities decreased by $1.3 million, or 12.2%, compared to June 30, 2023. As of December 31, 2023, our mortgage backed securities decreased by $2.0 million, or 17.0%, compared to December 31, 2022. During both periods, mortgage backed securities represented less than 2.0% of our securities portfolio.
Corporate bonds. Corporate bonds are debt obligations issued by companies to raise capital and refinance obligations of the issuer. As of June 30, 2024, our corporate bonds decreased by $13.0 million, or 10.7%, compared to June 30, 2023. As of December 31, 2023, our corporate bonds decreased by $10.0 million, or 8.0%, compared to December 31, 2022.
State and municipal securities. State and municipal securities are debt obligations issued by state and local governments. As of June 30, 2024, our state and municipal securities decreased by $6.8 million, or 3.0%, compared to June 30, 2023. As of December 31, 2023, our state and municipal securities decreased by $5.1 million, or 2.2%, compared to December 31, 2022.
Allowance for Credit Losses — Securities
Management measures expected credit losses on HTM debt securities on a collective basis by major security type (U.S. government and federal agencies, agency mortgage backed securities, corporate bonds and state and municipal securities). We estimate expected credit losses based on our historical credit loss information as adjusted for current conditions and reasonable and supportable forecasts. Securities issued by the U.S. Treasury or government agencies are not considered to be credit sensitive as they are explicitly or implicitly guaranteed by the U.S. government, and result in expectations of zero credit loss. Accordingly, management’s analysis of credit loss considers only the corporate and municipal segments. Accrued interest receivable on HTM debt securities totaled $1.6 million as of June 30, 2024 and as of December 31, 2023 and is excluded from the estimate of credit losses.
For AFS debt securities in an unrealized loss position, management first assesses whether it intends to sell, or if it is more likely than not that it will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is
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